HOUSTON - The Port of Houston, a 25-mile section of the 52-mile ship channel, tops the country in foreign waterborne tonnage, U.S. imports and U.S. export tonnage. The port generates $179 billion of state and $499 billion of national economic impact per year.

Ship channel investments through 2015 are likely to create 111,700 direct and 154,100 indirect jobs, according to the Greater Houston Port Bureau. Tax contributions are projected at $800 million, and the port is expected to be the site of $35 billion in capital and maintenance investments through 2015.

Most of the ship channel’s activity is driven by Houston’s $15 billion petrochemical complex. But among the more than 200 million tons of cargo moving through the port each year are items as diverse as steel, grain, electronics and clothing.

Growth along the ship channel, which is home to 150 companies, is driven by oil, gas and petrochemical firms. Houston-based Kinder Morgan Energy Partners LP is spending about $1.5 billion on multiple channel projects, said John Schlosser, president of Kinder Morgan Inc.’s terminals unit.

“Office-space market rents are increasing,” said John Talhelm, Houston-based senior vice president of Jones Lang LaSalle. “There are healthy shortages. We see low vacancy rates in almost every type of commercial product in Houston right now.”